British Waterways

When the Technical Services Survey Department of British Waterways was presented with an exciting new levelling project, they immediately considered the use of GPS. Their next step was to contact Survey Supplies, the distributor for Trimble’s Land Surveying equipment in England , Wales and Ireland for a full evaluation of the latest GPS levelling techniques; although equipped with other modern surveying systems, GPS was not yet part of their toolkit.

The Watergrid project has been set up by British Waterways to move water around their network in order to provide an alternative source of water supply to both industrial and domestic users. The survey aspect of the project involves levelling and detailing overflow weirs within the Watergrid network. Because of the large scale of the project it was decided to set up a trial survey area near Macclesfield to evaluate the use of GPS.

As a result of this evaluation, the survey team within British Waterways’ Technical Services Department (TSD) became the first survey organisation in the UK to purchase the new Trimble 5800 RTK rover, a cable-free, extremely lightweight GPS rover that incorporates Bluetooth wireless technology. Due to the large scale of the Watergrid project the decision has now been made to have all the survey work on the project undertaken by survey contractors. TSD are using their Trimble 5800 GPS system for quality control on Watergrid and other projects.

TSD provides technical and engineering support to British Waterways’ business nationwide, including civil, structural, geotechnical, mechanical and electrical engineering. A total of 85 technical and professional staff not only undertakes work for British Waterways but also for external clients both at home and abroad.

Land surveying is one of the specialist services offered by TSD, as are hydrographical surveying, information technology expertise and contract design, to name but a few. Stuart McKenzie is Principal Land Surveyor, he and his four colleagues carry out a full range of surveying and structural monitoring functions using some of the latest technology available but without GPS until this latest purchase. Stuart explains, “We have been actively considering the adoption of GPS for a number of years and have been monitoring the advances in this technology. GPS has been more fully developed, the equipment has become more reliable and lighter; coupled with the favourable results from the Watergrid trial project, we felt that now was the time to include GPS in our range of survey equipment. Another crucial factor in our decision to purchase the system at this time was the policy decision by the Ordnance Survey to cease supporting their benchmarks. GPS is a good way to measure reliably over longer survey sites, which canals can obviously be!”

“We also believe that GPS is now needed if a surveyor is to remain competitive in the market place and so we ordered the new Trimble cable-free system following the evaluation from Survey Supplies.”

“We prefer to promote survey equipment in the environment in which it will be used,” explains Matthew Lock, Technical Surveying Systems Sales Representative for Survey Supplies (Northern Region). “For the trial survey of the Watergrid project we established a series of Survey Control Stations and co-ordinated them to the Ordnance Survey Active Network. This not only produced an Elevation for each point related to the OS but also gave an Easting and Northing value, which could then be used for any subsequent Total Station work. We then compared the GPS processed elevations to traditional Precise Levelling and found very favourable results in a fraction of the observation time and with the added advantage of an Easting and Northing for each point.”

British Waterways purchased the new Trimble 5800 RTK rover consisting of a dual-frequency GPS receiver, an antenna, a UHF radio, a battery and a Bluetooth interface combined into a single 1.21kg unit that will fit into the palm of the hand; the receiver is designed to be used with Trimble’s new ACU Controller or TSCe Controller. At 3.57kg (the total weight of the receiver, ACU Controller, holder, rod and batteries to power a full day’s work) Trimble claims that this is the lightest complete RTK rover system yet available. There are no cables thanks to the built in short-range Bluetooth wireless technology. The new ACU features a colour, graphical Windows CE display and also operates Trimble 5600 and 3600 total stations.

TSD already uses a Geodimeter Total Station, the forerunner of the current Trimble 5603 direct reflex Autolock® total station; which also features in the team’s toolkit together with Trimble Terramodel software. “The new rover integrates well with our existing equipment and software,” Stuart continues, “we are completely happy with the system and plan to add OS digital mapping into the data logger, which will mean that we have no need to take any paper on site.” The work undertaken by Stuart’s team of late has been increasingly focused on the restoration of Britain ’s inland waterways, which has involved surveying a completely new route in cases where the old canal had been built over. These projects require conceptual or feasibility studies over distances sometimes in excess of 20km, a task that is proving to be easy with GPS.

A forthcoming large-scale project is the survey of five very remote reservoirs in Scotland to an accuracy of better than ± 20mm in order to provide reliable ordnance datum levels for monitoring purposes. Located near the Crinan canal in Argyllshire, the reservoirs have been difficult to survey by traditional means as the nearest triangulation point is several miles away over peat bogs and very arduous terrain; making the measurement of height transfer points unreliable and even potentially hazardous. Stuart concludes, “We have wanted to measure each of the five reservoirs to a reliable common datum for some time and are confident that the new Trimble GPS rover will be much easier to use than total stations in this environment, not only because of its technology but also the very light weight of the unit.”

In order to ensure that all users of Trimble GPS get the most from their equipment and have access to the best possible service and backup, Survey Supplies has a Dedicated Telephone Support Team based in the Liverpool head office as well as a Field Based Technical Support Representative and a Technical Sales Representative in each Region. When equipment is hired or purchased, training is undertaken by the Field Technical Support Representative at a location of the customers’ choice.